Phase coherent, low cost, 4th order XO

rick57 · 13th April 2003, 02:09 PM

Off the top of the head:

1. Rod Elliot’s ESP project
http://sound.westhost.com/project09.htm
Even with revision, modelling with circuit design shows that this is not phase coherent

2. Behringer 3-way CX (3400 ). http://www.behringer.com/02_products...X3400&lang=eng
Costs about the same as a Elliot ESP (including components about $US 150), ready made and adjustable.
But is it phase coherent?

3. DYO (Design your own) requires reasonable skill/ knowledge.

4. Other?

Non phase coherent XOs could be fixed, with phase correction.

Scenario A: Active

Scenario B: Passive
Best option

Richard

Elso Kwak · 13th April 2003, 02:59 PM

Hi Rick57,
How about Bessel characteristic?
What do you mean by phase coherent? I am not familiar with the term.

Hartono · 13th April 2003, 04:32 PM

Elso, maybe rick57 meant : phase coherent= minimum phase

Elso Kwak · 13th April 2003, 04:52 PM

Quote:

Originally posted by Hartono
Elso, maybe rick57 meant : phase coherent= minimum phase

Hi Hartono,
I am sorry what do you mean by Minimum Phase?. I am not familiar with the term....

Hartono · 13th April 2003, 05:05 PM

minimum phase , linear phase , phase coherent crossover
means that the crossover does not produce phase distortion

thus in systeum using XO with linear phase characteristic will produce summed output waveform with flat magnitude and phase characteristic.

traditionally this means using 1st order butterworth network, however some people have used various method to compensate for phase error in some active XO design so that the XO can be of higher order (steeper roll off) and still have the characteristic of 1st order butterworth network

I hope this might help

Pedja · 13th April 2003, 09:15 PM

Some other terms are in use also. There were good articles about it by John Kreskovsky, but unfortunately I just discovered he removed (it seems it happened yesterday!) whole content of his site. Phase coherent system is that which at its output shows the same relations between the phases as it was at the input. If phase coherent system has flat amplitude response then it can be considered as transient accurate, i.e. it will have good transient behavior. In itself, it is not an exclusive privilege of the first order crossovers.

Richard, you should ask this question rather in the loudspeaker forum. But, when you asked already…

I’d rather never use 24dB crossover. Be it active or passive, phase coherent or not.

When you correct phase of the non phase coherent crossover, you get the phase coherent crossover, we are walking in circle with it.

There is a bulk of the crossover simulators, so you can model crossover day and night. Linkwitz-Riley is not the only way to achieve phase coherent crossover.

Pedja

Hartono · 14th April 2003, 02:37 AM

nt

rick57 · 14th April 2003, 03:42 AM

See:

Which 4th order XOs are phase coherent? Are SWs of value?

Hartono · 14th April 2003, 04:57 AM

nt

rick57 · 14th April 2003, 05:00 AM

Maybe its not that relevent for music

13th April 2003, 02:09 PM	#1
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	Phase coherent, low cost, 4th order XO Off the top of the head: 1. Rod Elliot’s ESP project http://sound.westhost.com/project09.htm Even with revision, modelling with circuit design shows that this is not phase coherent 2. Behringer 3-way CX (3400 ). http://www.behringer.com/02_products...X3400&lang=eng Costs about the same as a Elliot ESP (including components about $US 150), ready made and adjustable. But is it phase coherent? 3. DYO (Design your own) requires reasonable skill/ knowledge. 4. Other? Non phase coherent XOs could be fixed, with phase correction. Scenario A: Active Scenario B: Passive Best option Richard

13th April 2003, 02:59 PM	#2
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	Bessel? Hi Rick57, How about Bessel characteristic? What do you mean by phase coherent? I am not familiar with the term.

13th April 2003, 04:32 PM	#3
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	1st order phase characteristic Elso, maybe rick57 meant : phase coherent= minimum phase

14th April 2003, 02:37 AM	#7
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	2nd & 4th order linkwitz rilley is not phase coherent nt

14th April 2003, 03:42 AM	#8
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	Is the test for "not phase coherent" valid See: Which 4th order XOs are phase coherent? Are SWs of value?


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13th April 2003, 05:05 PM	#5
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	minimum phase , linear phase , phase coherent crossover means that the crossover does not produce phase distortion thus in systeum using XO with linear phase characteristic will produce summed output waveform with flat magnitude and phase characteristic. traditionally this means using 1st order butterworth network, however some people have used various method to compensate for phase error in some active XO design so that the XO can be of higher order (steeper roll off) and still have the characteristic of 1st order butterworth network I hope this might help

13th April 2003, 09:15 PM	#6
Pedja diyAudio Member Join Date: Jun 2002 Location: Serbia	Some other terms are in use also. There were good articles about it by John Kreskovsky, but unfortunately I just discovered he removed (it seems it happened yesterday!) whole content of his site. Phase coherent system is that which at its output shows the same relations between the phases as it was at the input. If phase coherent system has flat amplitude response then it can be considered as transient accurate, i.e. it will have good transient behavior. In itself, it is not an exclusive privilege of the first order crossovers. Richard, you should ask this question rather in the loudspeaker forum. But, when you asked already… I’d rather never use 24dB crossover. Be it active or passive, phase coherent or not. When you correct phase of the non phase coherent crossover, you get the phase coherent crossover, we are walking in circle with it. There is a bulk of the crossover simulators, so you can model crossover day and night. Linkwitz-Riley is not the only way to achieve phase coherent crossover. Pedja

14th April 2003, 04:57 AM	#9
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	it the summed output doesn't resemble square wave then it's not phase coherent nt

14th April 2003, 05:00 AM	#10
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	Are u sure that the square wave is valid for music? (nt) Maybe its not that relevent for music

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